【作者】 张莹；

【导师】 李小明；

【作者基本信息】 湖南大学 ， 环境工程， 2008， 硕士

【摘要】 氯酚类化合物(CPs)被广泛用作木材防腐剂、防锈剂、杀菌剂和除草剂等,是毒性很高的物质,被美国EPA列入优先控制污染物的黑名单。氯酚类化合物的大量使用,使得大量的CPs污染物进入了环境,给自然环境造成很大的危害。含氯酚类废水的治理也受到越来越多的重视。微生物固定化技术因无二次污染、降解高效性和经济实用等优点而备受关注。可选择合适的载体来固定对CPs有降解作用的菌体,构成一种高效、快速、能连续处理的废水处理系统,可以有效地减少二次污染,处理含氯酚废水时效果良好,且已表现出了巨大的潜力,成为近年来国内外学者研究的热点。本研究采用新型生物载体丝瓜瓤作为固定载体,固定白腐菌中的一种黄孢原毛平革菌(Phanerochaete chrysosporium),控制条件使其在丝瓜瓤上生长,研究中发现其生长速度快,菌丝与载体结合紧密,单位面积菌体数量多。用此固定菌来降解废水中的2,4-二氯酚,探讨了两种固定化方法的可行性,绘制了固定化细胞和游离态细胞的生长曲线,研究了胞外酶和吸附在对2,4-二氯酚的去除中的作用,探讨了pH、温度、摇床转速、初始2,4-二氯酚对2,4-二氯酚降解的影响,并进行了固定化细胞流化床的研究,考察了不同水力停留时间(稀释率)和气体流量对处理效果的影响,并进行了动力学分析。结果表明,通过细胞培养过程中同时加入载体,使菌体附着在载体上生长方式实现了黄孢原毛平革菌的固定化,最大生物固定量为0.791g细胞/ g丝瓜瓤;固定化细胞生长速率和生长量均优于悬浮生长;含有胞外酶的培养基对2,4-二氯酚没有明显的降解作用;固定化细胞的最佳降解条件为温度35℃,pH为6,摇床转速为125/min。对于低浓度2,4-二氯酚,固定化细胞和游离细胞的降解速度相当;对于高浓度2,4-二氯酚,固定化细胞具有明显优势,不仅可以耐受更高浓度的2,4-二氯酚,其降解速率也高于游离细胞,最大降解速率是13.95mg/(L·d),是游离细胞的2倍。不同的水力停留时间(稀释率)和气体流量对固定化细胞流化床反应器连续处理2,4-二氯酚的降解效率有很大影响,固定化细胞对2,4-二氯酚降解过程遵循Monod方程,最大反应速率为7.002mg/(L·h),饱和常数为26.045 mg/L。更多还原

【Abstract】 Chlorophenols(CPs), extensively used as wood preservatives, rust inhibitors, fungicides and herbicides, is rated as a priority pollutant by the US Environmental Protection Agency because of this great ubiquity. The treatment of CPs polluted waste waters has attracted more and more attention. The commonly used procedures for removing CPs from wastewater include flocculation, adsorption, filtration, oxidation and biological treatments, among which biological methods using microorganisms are preferable because of their low cost, effectiveness and the low production of byproducts. The proper carrier could be employed to immobilze efficient microorganisms to form an effective and coutinous waste water treatment system, which has shown great potential and becomes a hotspot of research.Phanerochaete chrysosporium, one kind of whit rot fungi, was immobilized on loofa sponge, and was used to remove 2,4-DCP from the aqueous system. The feasibility of two immobilization methods was investigated. The growth curves of immobilized cell and the suspended cell were made. The role of extracellular enzymes in the 2,4-DCP removal was studied. The effects of pH, temperature and rotation speed on the biodegradation were discussed. The effects of residence time and gas flow rate on the biodegradation efficiency by immobilized cell fluid bed ractor were investigated. The kinetics of the immobilized fungus biodegradation on 2,4-DCP was analyzed.The results showed that the immobilization could be realized through the growth of the cell on loofa sponge and the biomass could reach 0.791g dry weight/(g sponge discs). The growth rate and the biomass of immobilized fungus were both better than that of suspended cells. The extracellular fluid showed negligible biodegradation of 2,4-DCP, which indicated that the extracellular enzymes were not directly involved in the biodegradation process. The optimum temperature, pH and rotation rate of shaking table for biodegradation by immobilized fungus were 35℃, 6.0 and 125r/min respectively. In sequential batch experiment, the bioactivity of immobilized cells was recovered and improved during the culture and the maximum degradation rate constant of 13.95 mg/(L·d) was reached in run 5. In continuous bioreactor test, the residence time and flow rate affected greatly on the behavior of fluidized bed reactor and the kinetic behavior of the loofa immobilized on loofa sponge was found to follow the Monod equation. The maximum reaction rate was 7.002mg/(L·h), and the saturation constant was 26.045 mg/L.更多还原